This disclosure relates to test and measurement instruments, in particular to test and measurement instruments and methods relating to post-acquisition trigger control and presentation of associated waveforms on a display.
Modern digital oscilloscopes can acquire an electrical signal under test and store digital data corresponding to the acquired signal as a data record. Such oscilloscopes can be used to display one or more waveforms while acquiring the electrical signal under test. In addition, the previously-stored digital data from the data record can be viewed as a waveform on a display of the oscilloscope even though acquisition of the electrical signal under test has stopped. While older oscilloscopes would generally acquire a relatively small data record corresponding to an amount of time that could be displayed, advancements in the areas of memory speed, memory capacity, and processor speed have led to newer oscilloscopes having improved functionality in this area. Consider that most digital oscilloscopes now have the capability of storing a significantly larger data record, which corresponds to more time than can reasonably be displayed at once.
As a result of the larger data records, additional functionality can be made available to the user. For example, most oscilloscopes allow a user to adjust a horizontal or vertical control, thereby changing a position of the waveform on the display. In addition, some oscilloscopes allow a user to “scroll” through the waveform—particularly after the data record has been acquired. However, since the data record now represents much more time than can be displayed at one time, the user's time interval of interest may be short compared to the full acquired record, and scrolling through an entire data record can be impractical. This causes difficulty in finding and analyzing the time interval of interest. Moreover, the full record may contain other events of interest that are different from the one event being displayed.
Some oscilloscopes provide a search feature to flag events of interest in the data record. But due to the rapid advancements in memory capacities, the size of data records continues to expand, which can hinder or otherwise slow down conventional search techniques. In addition, none of the conventional approaches provide for post-acquisition trigger events that are controlled and displayed intuitively by emulating a live trigger mode using standard trigger controls.